Endotracheal temperature and humidity measurements in laryngectomized patients: intra- and inter-patient variability

This study assesses intra- and inter-patient variability in endotracheal climate (temperature and humidity) and effects of heat and moister exchangers (HME) in 16 laryngectomized individuals, measured repeatedly (N = 47). Inhalation Breath Length (IBL) was 1.35 s without HME and 1.05 s with HME (P < 0.0001). With HME, end-inspiratory (minimum) humidity values increased 5.8 mg H2O/L (P < 0.0001) and minimum temperature values decreased 1.6°C (P < 0.0001). For the temperature and humidity minimums, the inter-patient variability was much smaller than the short- and long-term intra-patient variability. For exhalation breath length and full breath length, the opposite was the case. Conclusions: (1) Because inter-patient variability is smaller than intra-patient variability, investigating endotracheal climate in a limited number of laryngectomized subjects is justified, provided repeated measurements per patient are accomplished; (2) main contributor to intra-patient variability is the positioning of the catheter tip in the trachea; (3) an HME leads to a shortened IBL which enhances the HME effect.